1. Department of Respiratory Medicine, Navy General Hospital of the PLA, Beijing 100037, P.R. China
2. Department of Neurology, The First Hospital of Changsha, Changsha, Hunan 430100, P.R. China
3. Department of Emergency, The First Affiliated Hospital of Henan University of Science and Technology, Luoyang, Henan 471003, P.R. China
4. Department of Respiratory Medicine, The Sixth People's Hospital of Jinan City Affiliated to Jining Medical College, Jinan, Shandong 250200, P.R. China